Abstract

Smooth inactive ovaries (SIO) represent one of the main reproductive disorders limiting fertility in dairy cattle, leading to prolonged calving intervals and major economic losses. The present study evaluated the effectiveness of different hormonal and non-hormonal treatment regimens in reactivating ovarian function in lactating Holstein cows diagnosed with SIO. Eighty multiparous cows that failed to display estrus for 2–12 months postpartum were clinically examined and confirmed to have inactive ovaries and poorly toned uteri. Animals were randomly assigned to four groups (n = 20). Group 1 received a CIDR device combined with PGF₂α; Group 2 was treated with the Ovsynch (GPG) protocol; Group 3 received manual ovarian massage along with Tonophosphan and sodium dibasic phosphate; and Group 4 served as untreated controls. Estrus detection and AI were performed, with pregnancy confirmed 45 days post-insemination. The CIDR protocol produced the highest estrus response (80%) and total conception rate (75%). The GPG protocol yielded moderate results (60% response; 50% conception), whereas ovarian massage with mineral supplementation produced limited improvement (45% response; 25% conception). Control cows showed minimal reproductive recovery. These findings demonstrate that progesterone-based therapy is the most effective strategy for treating SIO and improving fertility outcomes.

Key words: dairy cows, smooth inactive ovaries, CIDR, Ovsynch, fertility, reproductive management